Conventionally, there have been known a pure electric vehicle in which the vehicle is driven using a driving force of a motor generator; a hybrid vehicle being driven by a combination of an engine, or an internal combustion engine, and a motor generator; and a fuel cell vehicle that is driven using power generated by a fuel cell, and so forth. Such a vehicle has a power control device, such as a booster converter, an inverter, and so forth, that receives power from a main battery or a fuel cell and controls power supply to the motor generator.
A power control device is also referred to as a PCU (a power control unit) for controlling a high voltage and a large current to be supplied to a motor generator, and needs to be mounted in an engine compartment in the vicinity of the motor generator. Therefore, in a hybrid vehicle that activates an engine by a motor generator, an engine activating auxiliary battery is mounted in a baggage compartment, as the auxiliary battery neither supplies power to a cell motor nor needs to be placed in the vicinity of the engine, and a space to place a PCU in an engine compartment needs to be ensured.
In recent years, size reduction of a high voltage instrument makes it possible to place an auxiliary battery in the vicinity of a power control device in an engine compartment. For example, Patent Document 1 discloses a technique for fastening a power control device reduced in size to a transaxle, in which the power control device has double axial first and second motor generators and a differential gear, and drives the first and second motor generators, the second motor generator being placed in parallel to the axis of the first motor generator, and the differential gear being placed on a third axis in parallel to these double axes.
However, in placing an auxiliary battery in the vicinity of a power control device, it is necessary to avoid interference between the auxiliary battery and the power control device, in order to ensure smooth protection of the power control device and smooth and rapid discharge from the power control device in the event of collision of the vehicle. In view of the above, Patent Document 2 discloses a separation mechanism for causing a relay box to move upward to be separated from the vehicle by a load transmitted via a guide surface from the auxiliary battery that moves backward upon invasion of a barrier (an obstacle) in a collision of the vehicle. Such a relay box separation structure can prevent interference between a vehicular instrument and other components that move upon application of an impact in a collision, whereby shock absorbing capability can be enhanced.
While damage resulting from a broken auxiliary battery is rather small as the auxiliary battery is at a rather low voltage; namely, 12 volts, it is desired to minimize damage to the power control device for controlling a high voltage of a few hundreds of volts. In view of the above, Patent Document 3 discloses an instrument mounting structure for protecting a power control device itself in a collision of a vehicle, in which the power control device is mounted such that the front end thereof is placed at a position more rearward in the vehicle than the front end of the transaxle, and a motor compressor is placed on a vehicle rearward side relative to the power control device.
Patent Document 4 discloses an inverter separation mechanism for protecting a power control device itself, such as an inverter or the like, by separating an inverter and an inverter bracket from an inverter tray mounted on a front member upon application of an external force to the inverter in a collision.